Devices for arresting blood loss and coagulating tissue are well known in the art. For example, several prior art instruments employ thermic coagulation (heated probes) to arrest bleeding. However, since the probe must come into close contact with the bleeding tissue, the probe may adhere to the eschar during probe removal possibly causing repeat bleeding. Other instruments direct high frequency electric current through the tissue to stop the bleeding. Again, eschar adherence may also be a problem with these instruments. In both types of instruments, the depth of the coagulation is difficult to control.
U.S. Pat. No. 5,207,675 to Canady attempts to resolve certain of the above-noted problems with respect to the prior art by providing a tube-like coagulation instrument in which an ionizable gas is forced through the instrument and ionized by an electrode prior to the gas exiting the distal end of the instrument towards the bleeding tissue.
U.S. Pat. No. 5,720,745 to Farin et al. discloses a coagulation instrument which extends through a working channel of an endoscope and includes an electrode for ionizing a stream of ionizable gas exiting the distal end of the instrument at a rate of less than about 1 liter/minute. As explained in great detail in the Farin et al. specification, the purpose of discharging the gas at a very low flow rate is to effectively cloud the tissue area and create an ionizable gas "atmosphere" to gently coagulate the tissue. In both of the above patents, the electrodes are not designed to come into direct contact with the tissue.
However, using these instruments to treat certain more tubular sites, e.g., the esophagus and/or colon, is often difficult, impractical and time consuming and may cause unintended collateral damage to the surrounding tissue. For example, the longitudinally oriented instrument fires the ionizable gas and the RF energy in an axial direction from its distal end which, in the case of tubular tissue, would be parallel to the bleeding tissue. Thus, focusing the energy transversely at the bleeding tissue may be very difficult using this instrument and may cause collateral tissue damage.
Thus, a need exists for the development of a new and effective instrument for treating certain more tubular tissue.